Internal gears for a planetary transmission may require that each of the internal gears be connected to a cap, or similar part, which closes off one end of the internal gear. The cap enables axial thrust forces of the gear to be counteracted and defines a thru-hole and other rotating components within the transmission pass through the thru-hole. The internal gear includes a body that surrounds an axis of rotation and the body extends between opposing ends. Splines and/or gears are spaced circumferentially on the body and extend about the axis. One of the ends defines a groove that extends to a floor and the groove surrounds the axis. A lip extends upward from the floor of the groove and surrounds the groove in spaced relationship to the axis. The lip defines a channel that extends perpendicular to the axis and surrounds the groove. The cap includes a flange that extends about the periphery. The cap is typically attached to the gear by inserting the flange in the groove of the gear. A snap ring is inserted into the channel to capture the flange between the snap ring and the floor of the groove and retain the cap to the gear in the axial direction. Additionally, the flange and the lip each define teeth that are complimentary to one another. Therefore, the teeth of the flange and the teeth of the lip mesh when the cap is inserted into the groove to prevent axial rotation of the cap relative to the gear.